Magnetic sensor having enhanced linearization by applied field angle rotation

Abstract

Method and apparatus for a current sensing device including a magnetoresistive magnetic field sensing element positioned with respect to a shaped conductor such that an applied field generated by current through the shaped conductor forms an offset angle theta defined by the applied field and a field of a pinning layer of the magnetoresistive element. The offset angle increases a linearity of the device output for current in the shaped conductor flowing in a first direction. A further sensor can increase linearity in the opposite direction.

What is claimed is: 
     
       1. A device, comprising:
 a first magnetoresistive magnetic field sensing element positioned with respect to a shaped conductor such that an applied field generated by current through the shaped conductor forms an offset angle theta defined by the applied field and a field of a first pinned layer of the first magnetoresistive magnetic field sensing element, wherein the offset angle theta is greater than about five degrees to increase a linearity of an output of the first magnetoresistive magnetic field sensing element for current in the shaped conductor flowing in a first direction; and 
 an output module to receive the output of the first magnetoresistive magnetic field sensing element and provide a device output signal, 
 wherein the shaped conductor comprises an arcuate portion coupled at each end to respective linear portions, and wherein the first magnetic field sensing element comprises a GMR having elements in a bridge configuration such that at least some of the elements in the bridge configuration are positioned on the arcuate portion of the shaped conductor. 
 
     
     
       2. The device according to  claim 1 , wherein the GMR element comprises a second pinned layer providing a reference field substantially perpendicular to the field of the first pinned layer. 
     
     
       3. The device according to  claim 1 , wherein the first magnetic field sensing element comprises magnetic sensors arranged in a Wheatstone bridge configuration. 
     
     
       4. The device according to  claim 3 , wherein first and second ones of the magnetic sensors are magnetically shielded for linear field sensing. 
     
     
       5. The device according to  claim 1 , wherein a supply voltage controls a gain of the magnetic field sensing element over temperature. 
     
     
       6. The device according to  claim 1 , wherein a direction of current flow in the shaped conductor is determined in the bridge configuration. 
     
     
       7. The device according to  claim 1 , further including a second magnetoresistive magnetic field sensing element to increase linearity of the output for current flow in the shaped conductor in the opposite direction. 
     
     
       8. The device according to  claim 7 , wherein an applied angle for the second magnetoresistive magnetic field sensing element is about equal to 180 minus theta, where theta is the applied angle for the first magnetoresistive magnetic field sensing element. 
     
     
       9. The device according to  claim 7 , wherein the first magnetoresistive magnetic field sensing element has a die orientation 180 degrees to the second magnetoresistive magnetic field sensing element. 
     
     
       10. A device, comprising:
 a first magnetic field sensor means for sensing current in a shaped conductor at an offset angle theta defined by an applied field and a field of a first pinned layer of the first magnetic field sensor means, wherein the offset angle theta is greater than about five degrees to increase a linearity of an output of the first magnetic field sensor means for current in the shaped conductor flowing in a first direction; and 
 an output module to receive the output of the magnetic field sensor means and provide a device output signal, 
 wherein the shaped conductor comprises an arcuate portion coupled at each end to respective linear portions, and wherein the first magnetic field sensor means comprises a GMR having elements in a bridge configuration such that at least some of the elements in the bridge configuration are positioned on the arcuate portion of the shaped conductor. 
 
     
     
       11. The device according to  claim 10 , further including a second magnetic field sensor means for increasing linearity of the output for current flow in the shaped conductor in the opposite direction. 
     
     
       12. The device according to  claim 10 , wherein the GMR element comprises a second pinned layer providing a reference field substantially perpendicular to the field of the first pinned layer. 
     
     
       13. The device according to  claim 10 , wherein the first magnetic field sensor means comprises magnetic sensors arranged in a Wheatstone bridge configuration. 
     
     
       14. The device according to  claim 13 , wherein a direction of current flow in the shaped conductor is determined in the bridge configuration. 
     
     
       15. A method, comprising:
 positioning a first magnetoresistive magnetic field sensing element with respect to a shaped conductor such that an applied field generated by current through the shaped conductor forms an offset angle theta defined by the applied field and a field of a first pinned layer of the first magnetoresistive magnetic field sensing element, wherein the offset angle theta is greater than about five degrees to increase a linearity of an output of the first magnetoresistive magnetic field sensing element for current in the shaped conductor flowing in a first direction; and 
 employing an output module to receive the output of the first magnetoresistive magnetic field sensing element and provide a device output signal, 
 wherein the shaped conductor comprises an arcuate portion coupled at each end to respective linear portions, and wherein the first magnetic field sensing element comprises a GMR having elements in a bridge configuration such that at least some of the elements in the bridge configuration are positioned on the arcuate portion of the shaped conductor. 
 
     
     
       16. The method according to  claim 15 , further including positioning a second magnetoresistive magnetic field sensing element to increase linearity of the output for current flow in the shaped conductor in the opposite direction. 
     
     
       17. The method according to  claim 15 , wherein the first magnetoresistive magnetic field sensing element comprises magnetic sensors arranged in a Wheatstone bridge configuration. 
     
     
       18. The method according to  claim 17 , further including determining a direction of current flow in the shaped conductor in the Wheatstone bridge configuration. 
     
     
       19. The method according to  claim 15 , further including positioning a second magnetoresistive magnetic field sensing element to increase linearity of the output for current flow in the shaped conductor in the opposite direction, determining a direction of current flow in the shaped conductor in the bridge configuration, and switching between the first and second magnetoresistive magnetic field sensing elements depending on the direction of current flow.